Inkjet printhead having nozzle arrangements with actuator pivot anchors

ABSTRACT

Provided is an inkjet printhead having a plurality of nozzle arrangements for ejecting ink onto a printing medium. Each nozzle arrangement includes a substrate defining an ink chamber having an ink inlet and a plurality of ink ejection ports, the chamber and ink supply channel being in fluid communication via the ink inlet. Each arrangement also includes a pivot anchor arranged on the substrate, and an actuator fast with the pivot anchor and arranged to cause selective ejection of ink from any one of the ejection ports while simultaneously causing an inflow of ink from the ink supply channel into the chamber via the ink inlet.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.11/144,799 filed on Jun. 6, 2005, now issued U.S. Pat. No. 7,416,282,which is a continuation of U.S. application Ser. No. 10/882,772 filed onJul. 2, 2004, now issued as U.S. Pat. No. 6,938,990, which is acontinuation of U.S. application Ser. No. 10/302,604 filed on Nov. 23,2002, now issued as U.S. Pat. No. 6,787,051, which is a continuation ofU.S. application Ser. No. 09/112,801 filed on Jul. 10, 1998, now issuedas U.S. Pat. No. 6,491,833, the entire contents of which are hereinincorporated by reference.

The following Australian provisional patent applications are herebyincorporated by cross-reference. For the purposes of location andidentification, US patent applications identified by their US patentapplication serial numbers (USSN) are listed alongside the Australianapplications from which the US patent applications claim the right ofpriority. from which the US patents/patent applications claim the rightof priority.

CROSS- REFERENCED US PATENT/PATENT AUSTRALIAN APPLICATION (CLAIMINGPROVISIONAL RIGHT OF PRIORITY FROM PATENT AUSTRALIAN PROVISIONALAPPLICATION NO. APPLICATION) PO7991 6,750,901 PO8505 6,476,863 PO79886,788,336 PO9395 6,322,181 PO8017 6,597,817 PO8014 6,227,648 PO80256,727,948 PO8032 6,690,419 PO7999 6,727,951 PO8030 6,196,541 PO79976,195,150 PO7979 6,362,868 PO7978 6,831,681 PO7982 6,431,669 PO79896,362,869 PO8019 6,472,052 PO7980 6,356,715 PO8018 6,894,694 PO79386,636,216 PO8016 6,366,693 PO8024 6,329,990 PO7939 6,459,495 PO85016,137,500 PO8500 6,690,416 PO7987 7,050,143 PO8022 6,398,328 PO84977,110,024 PO8020 6,431,704 PO8504 6,879,341 PO8000 6,415,054 PO79346,665,454 PO7990 6,542,645 PO8499 6,486,886 PO8502 6,381,361 PO79816,317,192 PO7986 6,850,274 PO7983 09/113,054 PO8026 6,646,757 PO80286,624,848 PO9394 6,357,135 PO9397 6,271,931 PO9398 6,353,772 PO93996,106,147 PO9400 6,665,008 PO9401 6,304,291 PO9403 6,305,770 PO94056,289,262 PP0959 6,315,200 PP1397 6,217,165 PP2370 6,786,420 PO80036,350,023 PO8005 6,318,849 PO8066 6,227,652 PO8072 6,213,588 PO80406,213,589 PO8071 6,231,163 PO8047 6,247,795 PO8035 6,394,581 PO80446,244,691 PO8063 6,257,704 PO8057 6,416,168 PO8056 6,220,694 PO80696,257,705 PO8049 6,247,794 PO8036 6,234,610 PO8048 6,247,793 PO80706,264,306 PO8067 6,241,342 PO8001 6,247,792 PO8038 6,264,307 PO80336,254,220 PO8002 6,234,611 PO8068 6,302,528 PO8062 6,283,582 PO80346,239,821 PO8039 6,338,547 PO8041 6,247,796 PO8004 6,557,977 PO80376,390,603 PO8043 6,362,843 PO8042 6,293,653 PO8064 6,312,107 PO93896,227,653 PO9391 6,234,609 PP0888 6,238,040 PP0891 6,188,415 PP08906,227,654 PP0873 6,209,989 PP0993 6,247,791 PP0890 6,336,710 PP13986,217,153 PP2592 6,416,167 PP2593 6,243,113 PP3991 6,283,581 PP39876,247,790 PP3985 6,260,953 PP3983 6,267,469 PO7935 6,224,780 PO79366,235,212 PO7937 6,280,643 PO8061 6,284,147 PO8054 6,214,244 PO80656,071,750 PO8055 6,267,905 PO8053 6,251,298 PO8078 6,258,285 PO79336,225,138 PO7950 6,241,904 PO7949 6,299,786 PO8060 6,866,789 PO80596,231,773 PO8073 6,190,931 PO8076 6,248,249 PO8075 6,290,862 PO80796,241,906 PO8050 6,565,762 PO8052 6,241,905 PO7948 6,451,216 PO79516,231,772 PO8074 6,274,056 PO7941 6,290,861 PO8077 6,248,248 PO80586,306,671 PO8051 6,331,258 PO8045 6,110,754 PO7952 6,294,101 PO80466,416,679 PO9390 6,264,849 PO9392 6,254,793 PP0889 6,235,211 PP08876,491,833 PP0882 6,264,850 PP0874 6,258,284 PP1396 6,312,615 PP39896,228,668 PP2591 6,180,427 PP3990 6,171,875 PP3986 6,267,904 PP39846,245,247 PP3982 6,315,914 PP0895 6,231,148 PP0869 6,293,658 PP08876,614,560 PP0885 6,238,033 PP0884 6,312,070 PP0886 6,238,111 PP08776,378,970 PP0878 6,196,739 PP0883 6,270,182 PP0880 6,152,619 PO80066,087,638 PO8007 6,340,222 PO8010 6,041,600 PO8011 6,299,300 PO79476,067,797 PO7944 6,286,935 PO7946 6,044,646 PP0894 6,382,769

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to the field of inkjet printing and, inparticular, discloses a method of manufacturing amicro-electromechanical fluid ejecting device.

BACKGROUND OF THE INVENTION

Many ink jet printing mechanisms are known. Unfortunately, in massproduction techniques, the production of ink jet heads is quitedifficult. For example, often, the orifice or nozzle plate isconstructed separately from the ink supply and ink ejection mechanismand bonded to the mechanism at a later stage (Hewlett-Packard Journal,Vol. 36 no 5, pp 33-37 (1985)). The separate material processing stepsrequired in handling such precision devices often add a substantialexpense in manufacturing.

Additionally, side shooting ink jet technologies (U.S. Pat. No.4,899,181) are often used but again, this limits the amount of massproduction throughput given any particular capital investment.

Additionally, more esoteric techniques are also often utilized. Thesecan include electroforming of nickel stage (Hewlett-Packard Journal,Vol. 36 no 5, pp 33-37 (1985)), electro-discharge machining, laserablation (U.S. Pat. No. 5,208,604), micro-punching, etc.

The utilization of the above techniques is likely to add substantialexpense to the mass production of ink jet print heads and therefore addsubstantially to their final cost.

It would therefore be desirable if an efficient system for the massproduction of ink jet print heads could be developed.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there isprovided a method of manufacturing a Dual Chamber Single VerticalActuator Ink Jet Printer print head wherein an array of nozzles areformed on a substrate utilizing planar monolithic deposition,lithographic and etching processes. Preferably, multiple ink jet headsare formed simultaneously on a single planar substrate such as a siliconwafer.

The print heads can be formed utilizing standard vlsi/ulsi processingand can include integrated drive electronics formed on the samesubstrate. The drive electronics preferably being of a CMOS type. In thefinal construction, ink can be ejected from the substrate substantiallynormal to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

FIG. 1 shows a schematic side view of an ink jet nozzle of the inventionin a quiescent state;

FIG. 2 shows a schematic side view of the nozzle in an initial part ofan ink ejection stage;

FIG. 3 shows a schematic side view of the nozzle in a further part of anink ejection stage;

FIG. 4 shows a schematic side view of the nozzle in a final part of anink ejection stage;

FIG. 5 shows a schematic side view of the nozzle again in its quiescentstate;

FIG. 6 illustrates a side perspective view, of a single nozzlearrangement of the preferred embodiment.

FIG. 7 illustrates a perspective view, partly in section of a singlenozzle arrangement of the preferred embodiment;

FIG. 8 shows a schematic side view of an initial stage in themanufacture of an ink jet nozzle of the invention with the deposition ofa CMOS layer;

FIG. 9 shows a step of an initial etch to form a nozzle chamber;

FIG. 10 shows a step of depositing a first sacrificial layer;

FIG. 11 shows a step of etching the first sacrificial layer;

FIG. 12 shows a step of depositing a glass layer;

FIG. 13 shows a step of etching the glass layer;

FIG. 14 shows a step of depositing an actuator material layer;

FIG. 15 shows a step of planarizing the actuating material layers;

FIG. 16 shows a step of depositing a heater material layer;

FIG. 17 shows a step of depositing a further glass layer;

FIG. 18 shows a step of depositing a further heater material layer;

FIG. 19 shows a step of planarizing the further heater material layer;

FIG. 20 shows a step of depositing yet another glass layer;

FIG. 21 shows a step of etching said another glass layer;

FIG. 22 shows a step of etching the other glass layers;

FIG. 23 shows a step of depositing a further sacrificial layer;

FIG. 24 shows a step of forming a nozzle chamber;

FIG. 25 shows a step of forming nozzle openings;

FIG. 26 shows a step of back etching the substrate; and

FIG. 27 shows a final step of etching the sacrificial layers;

FIG. 28 illustrates a part of an array view of a portion of a printheadas constructed in accordance with the principles of the presentinvention;

FIG. 29 provides a legend of the materials indicated in FIGS. 30 to 42;and

FIG. 30 shows a sectional side view of an initial manufacturing step ofan ink jet printhead nozzle showing a silicon wafer with a buriedepitaxial layer and an electrical circuitry layer;

FIG. 31 shows a step of etching the oxide layer;

FIG. 32 shows a step of etching an exposed part of the silicon layer;

FIG. 33 shows a step of depositing a second sacrificial layer;

FIG. 34 shows a step of etching the first sacrificial layer;

FIG. 35 shows a step of etching the second sacrificial layer;

FIG. 36 shows the step of depositing a heater material layer;

FIG. 37 shows a step of depositing a further heater material layer;

FIG. 38 shows a step of etching a glass layer;

FIG. 39 shows a step of depositing a further glass layer;

FIG. 40 shows a step of etching the further glass layer;

FIG. 41 shows a step of further etching the further glass layer;

FIG. 42 shows a step of back etching through the silicon layer;

FIG. 43 shows a step of etching the sacrificial layers; and

FIG. 44 shows a step of filling the completed ink jet nozzle with ink.—

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the preferred embodiment, there is provided an inkjet printheadhaving an array of nozzles wherein the nozzles are grouped in pairs andeach pair is provided with a single actuator which is actuated so as tomove a paddle type mechanism to force the ejection of ink out of one orother of the nozzle pairs. The paired nozzles eject ink from a singlenozzle chamber which is re-supplied by means of an ink supply channel.Further, the actuator of the preferred embodiment has uniquecharacteristics so as to simplify the actuation process.

Turning initially to FIGS. 1 to 5, there will now be explained theprinciples of operation of the preferred embodiment. In the preferredembodiment, a single nozzle chamber 1 is utilized to supply ink to twoink ejection nozzles 2, 3. Ink is re-supplied to the nozzle chamber 1via means of an ink supply channel 5. In its quiescent position, two inkmenisci 6, 7 are formed around the ink ejection holes 2, 3. Thearrangement of FIG. 1 being substantially axially symmetric around acentral paddle 9 which is attached to an actuator mechanism.

When it is desired to eject ink out of one of the nozzles, say nozzle 3,the paddle 9 is actuated so that it begins to move as indicated in FIG.2. The movement of paddle 9 in the direction 10 results in a generalcompression of the ink on the right hand side of the paddle 9. Thecompression of the ink results in the meniscus 7 growing as the ink isforced out of the nozzles 3. Further, the meniscus 6 undergoes aninversion as the ink is sucked back on the left hand side of theactuator 10 with additional ink 12 being sucked in from ink supplychannel 5. The paddle actuator 9 eventually comes to rest and begins toreturn as illustrated in FIG. 3. The ink 13 within meniscus 7 hassubstantial forward momentum and continues away from the nozzle chamberwhilst the paddle 9 causes ink to be sucked back into the nozzlechamber. Further, the surface tension on the meniscus 6 results infurther in flow of the ink via the ink supply channel 5. The resolutionof the forces at work in the resultant flows results in a generalnecking and subsequent breaking of the meniscus 7 as illustrated in FIG.4 wherein a drop 14 is formed which continues onto the media or thelike. The paddle 9 continues to return to its quiescent position.

Next, as illustrated in FIG. 5, the paddle 9 returns to its quiescentposition and the nozzle chamber refills by means of surface tensioneffects acting on meniscuses 6, 7 with the arrangement of returning tothat showing in FIG. 1. When required, the actuator 9 can be activatedto eject ink out of the nozzle 2 in a symmetrical manner to thatdescribed with reference to FIGS. 1-5. Hence, a single actuator 9 isactivated to provide for ejection out of multiple nozzles. The dualnozzle arrangement has a number of advantages including in that movementof actuator 9 does not result in a significant vacuum forming on theback surface of the actuator 9 as a result of its rapid movement.Rather, meniscus 6 acts to ease the vacuum and further acts as a “pump”for the pumping of ink into the nozzle chamber. Further, the nozzlechamber is provided with a lip 15 (FIG. 2) which assists in equalizingthe increase in pressure around the ink ejection holes 3 which allowsfor the meniscus 7 to grow in an actually symmetric manner therebyallowing for straight break off of the drop 14.

Turning now to FIGS. 6 and 7, there is illustrated a suitable nozzlearrangement with FIG. 6 showing a single side perspective view and FIG.7 showing a view, partly in section illustrating the nozzle chamber. Theactuator 20 includes a pivot arm attached at the post 21. The pivot armincludes an internal core portion 22 which can be constructed fromglass. On each side 23, 24 of the internal portion 22 is two separatelycontrol heater arms which can be constructed from an alloy of copper andnickel (45% copper and 55% nickel). The utilization of the glass core isadvantageous in that it has a low coefficient thermal expansion andcoefficient of thermal conductivity. Hence, any energy utilized in theheaters 23, 24 is substantially maintained in the heater structure andutilized to expand the heater structure and opposed to an expansion ofthe glass core 22. Structure or material chosen to form part of theheater structure preferably has a high “bend efficiency”. One form ofdefinition of bend efficiency can be the Young's modulus times thecoefficient of thermal expansion divided by the density and by thespecific heat capacity.

The copper nickel alloy in addition to being conductive has a highcoefficient of thermal expansion, a low specific heat and density inaddition to a high Young's modulus. It is therefore a highly suitablematerial for construction of the heater element although other materialswould also be suitable.

Each of the heater elements can comprise a conductive out and returntrace with the traces being insulated from one and other along thelength of the trace and conductively joined together at the far end ofthe trace. The current supply for the heater can come from a lowerelectrical layer via the pivot anchor 21. At one end of the actuator 20,there is provided a bifurcated portion 30 which has attached at one endthereof to leaf portions 31, 32.

To operate the actuator, one of the arms 23, 24 e.g. 23 is heated in airby passing current through it. The heating of the arm results in ageneral expansion of the arm. The expansion of the arm results in ageneral bending of the arm 20. The bending of the arm 20 further resultsin leaf portion 32 pulling on the paddle portion 9. The paddle 9 ispivoted around a fulcrum point by means of attachment to leaf portions38, 39 which are generally thin to allow for minor flexing. The pivotingof the arm 9 causes ejection of ink from the nozzle hole 40. The heateris deactivated resulting in a return of the actuator 20 to its quiescentposition and its corresponding return of the paddle 9 also to isquiescent position. Subsequently, to eject ink out of the other nozzlehole 41, the heater 24 can be activated with the paddle operating in asubstantially symmetric manner.

It can therefore be seen that the actuator can be utilized to move thepaddle 9 on demand so as to eject drops out of the ink ejection holee.g. 40 with the ink refilling via an ink supply channel 44 locatedunder the paddle 9.

The nozzle arrangement of the preferred embodiment can be formed on asilicon wafer utilizing standard semi-conductor fabrication processingsteps and micro-electromechanical systems (MEMS) constructiontechniques.

For a general introduction to a micro-electro mechanical system (MEMS)reference is made to standard proceedings in this field including theproceeding of the SPIE (International Society for Optical Engineering)including volumes 2642 and 2882 which contain the proceedings of recentadvances and conferences in this field.

Preferably, a large wafer of printheads is constructed at any one timewith each printhead providing a predetermined pagewidth capabilities anda single printhead can in turn comprise multiple colors so as to providefor full color output as would be readily apparent to those skilled inthe art.

Turning now to FIG. 8—FIG. 27 there will now be explained one form offabrication of the preferred embodiment. The preferred embodiment canstart as illustrated in FIG. 8 with a CMOS processed silicon wafer 50which can include a standard CMOS layer 51 including of the relevantelectrical circuitry etc. The processing steps can then be as follows:

-   1. As illustrated in FIG. 9, a deep etch of the nozzle chamber 98 is    performed to a depth of 25 micron;-   2. As illustrated in FIG. 10, a 27 micron layer of sacrificial    material 52 such as aluminum is deposited;-   3. As illustrated in FIG. 11, the sacrificial material is etched to    a depth of 26 micron using a glass stop so as to form cavities using    a paddle and nozzle mask.-   4. As illustrated in FIG. 12, a 2 micron layer of low stress glass    53 is deposited.-   5. As illustrated in FIG. 13, the glass is etched to the aluminum    layer utilizing a first heater via mask.-   6. As illustrated in FIG. 14, a 2-micron layer of 60% copper and 40%    nickel is deposited 55 and planarized (FIG. 15) using chemical    mechanical planarization (CMP).-   7. As illustrated in FIG. 16, a 0.1 micron layer of silicon nitride    is deposited 56 and etched using a heater insulation mask.-   8. As illustrated in FIG. 17, a 2-micron layer of low stress glass    57 is deposited and etched using a second heater mask.-   9. As illustrated in FIG. 18, a 2-micron layer of 60% copper and 40%    nickel 58 is deposited and planarized (FIG. 19) using chemical    mechanical planarization.-   10. As illustrated in FIG. 20, a 1-micron layer of low stress glass    60 is deposited and etched (FIG. 21) using a nozzle wall mask.-   11. As illustrated in FIG. 22, the glass is etched down to the    sacrificial layer using an actuator paddle wall mask.-   12. As illustrated in FIG. 23, a 5-micron layer of sacrificial    material 62 is deposited and planarized using CMP.-   13. As illustrated in FIG. 24, a 3-micron layer of low stress glass    63 is deposited and etched using a nozzle rim mask.-   14. As illustrated in FIG. 25, the glass is etched down to the    sacrificial layer using nozzle mask.-   15. As illustrated in FIG. 26, the wafer can be etched from the back    using a deep silicon trench etcher such as the Silicon Technology    Systems deep trench etcher.-   16. Finally, as illustrated in FIG. 27, the sacrificial layers are    etched away releasing the ink jet structure.

Subsequently, the print head can be washed, mounted on an ink chamber,relevant electrical interconnections TAB bonded and the print headtested.

Turning now to FIG. 28, there is illustrated a portion 80 of a fullcolor printhead which is divided into three series of nozzles 71, 72 and73. Each series can supply a separate color via means of a correspondingink supply channel. Each series is further subdivided into two sub rowse.g. 76, 77 with the relevant nozzles of each sub row being firedsimultaneously with one sub row being fired a predetermined time after asecond sub row such that a line of ink drops is formed on a page.

As illustrated in FIG. 28 the actuators are formed in a curvedrelationship with respect to the main nozzle access so as to provide fora more compact packing of the nozzles. Further, the block portion (21 ofFIG. 6) is formed in the wall of an adjacent series with the blockportion of the row 73 being formed in a separate guide rail 80 providedas an abutment surface for the TAB strip when it is abutted against theguide rail 80 so as to provide for an accurate registration of the tabstrip with respect to the bond pads 81, 82 which are provided along thelength of the printhead so as to provide for low impedance driving ofthe actuators.

The principles of the preferred embodiment can obviously be readilyextended to other structures. For example, a fulcrum arrangement couldbe constructed which includes two arms which are pivoted around athinned wall by means of their attachment to a cross bar. Each arm couldbe attached to the central cross bar by means of similarly leafedportions to that shown in FIG. 6 and FIG. 7. The distance between afirst arm and the thinned wall can be L units whereas the distancebetween the second arm and wall can be NL units. Hence, when atranslational movement is applied to the second arm for a distance ofN×X units the first arm undergoes a corresponding movement of X units.The leafed portions allow for flexible movement of the arms whilstproviding for full pulling strength when required.

It would be evident to those skilled in the art that the presentinvention can further be utilized in either mechanical arrangementrequiring the application forces to induce movement in a structure.

One form of detailed manufacturing process which can be used tofabricate monolithic ink jet print heads operating in accordance withthe principles taught by the present embodiment can proceed utilizingthe following steps:

-   1. Using a double sided polished wafer 50, complete drive    transistors, data distribution, and timing circuits using a 0.5    micron, one poly, 2 metal CMOS process 51. Relevant features of the    wafer at this step are shown in FIG. 30. For clarity, these diagrams    may not be to scale, and may not represent a cross section though    any single plane of the nozzle. FIG. 29 is a key to representations    of various materials in these manufacturing diagrams, and those of    other cross-referenced ink jet configurations.-   2. Etch oxide down to silicon or aluminum using Mask 1. This mask    defines the ink inlet, the heater contact vias, and the edges of the    print head chips. This step is shown in FIG. 31.-   3. Etch exposed silicon 51 to a depth of 20 microns. This step is    shown in FIG. 32.-   4. Deposit a 1-micron conformal layer of a first sacrificial    material 91.-   5. Deposit 20 microns of a second sacrificial material 92, and    planarize down to the first sacrificial layer using CMP. This step    is shown in FIG. 33.-   6. Etch the first sacrificial layer using Mask 2, defining the    nozzle chamber wall 93, the paddle 9, and the actuator anchor point    21. This step is shown in FIG. 34.-   7. Etch the second sacrificial layer down to the first sacrificial    layer using Mask 3. This mask defines the paddle 9. This step is    shown in FIG. 35.-   8. Deposit a 1-micron conformal layer of PECVD glass 53.-   9. Etch the glass using Mask 4, which defines the lower layer of the    actuator loop.-   10. Deposit 1 micron of heater material 55, for example titanium    nitride (TiN) or titanium diboride (TiB2). Planarize using CMP. This    step is shown in FIG. 36.-   11. Deposit 0.1 micron of silicon nitride 56.-   12. Deposit 1 micron of PECVD glass 57.-   13. Etch the glass using Mask 5, which defines the upper layer of    the actuator loop.-   14. Etch the silicon nitride using Mask 6, which defines the vias    connecting the upper layer of the actuator loop to the lower layer    of the actuator loop.-   15. Deposit 1 micron of the same heater material 58 previously    deposited. Planarize using CMP. This step is shown in FIG. 37.-   16. Deposit 1 micron of PECVD glass 60.-   17. Etch the glass down to the sacrificial layer using Mask 6. This    mask defines the actuator and the nozzle chamber wall, with the    exception of the nozzle chamber actuator slot. This step is shown in    FIG. 38.-   18. Wafer probe. All electrical connections are complete at this    point, bond pads are accessible, and the chips are not yet    separated.-   19. Deposit 4 microns of sacrificial material 62 and planarize down    to glass using CMP.-   20. Deposit 3 microns of PECVD glass 63. This step is shown in FIG.    39.-   21. Etch to a depth of (approx.) 1 micron using Mask 7. This mask    defines the nozzle rim 95. This step is shown in FIG. 40.-   22. Etch down to the sacrificial layer using Mask 8. This mask    defines the roof of the nozzle chamber, and the nozzle 40, 41    itself. This step is shown in FIG. 41.-   23. Back-etch completely through the silicon wafer (with, for    example, an ASE Advanced Silicon Etcher from Surface Technology    Systems) using Mask 9. This mask defines the ink inlets 65 which are    etched through the wafer. The wafer is also diced by this etch. This    step is shown in FIG. 42.-   24. Etch both types of sacrificial material. The nozzle chambers are    cleared, the actuators freed, and the chips are separated by this    etch. This step is shown in FIG. 43.-   25. Mount the print heads in their packaging, which may be a molded    plastic former incorporating ink channels which supply the    appropriate color ink 96 to the ink inlets at the back of the wafer.-   26. Connect the print heads to their interconnect systems. For a low    profile connection with minimum disruption of airflow, TAB may be    used. Wire bonding may also be used if the printer is to be operated    with sufficient clearance to the paper.-   27. Hydrophobize the front surface of the print heads.-   28. Fill the completed print heads with ink and test them. A filled    nozzle is shown in FIG. 44.

The presently disclosed ink jet printing technology is potentiallysuited to a wide range of printing system including: color andmonochrome office printers, short run digital printers, high speeddigital printers, offset press supplemental printers, low cost scanningprinters high speed pagewidth printers, notebook computers with in-builtpagewidth printers, portable color and monochrome printers, color andmonochrome copiers, color and monochrome facsimile machines, combinedprinter, facsimile and copying machines, label printers, large formatplotters, photograph copiers, printers for digital photographic“minilabs”, video printers, PhotoCD printers, portable printers forPDAs, wallpaper printers, indoor sign printers, billboard printers,fabric printers, camera printers and fault tolerant commercial printerarrays.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects to be illustrative andnot restrictive.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Ofcourse many different devices could be used. However presently popularink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption.This is approximately 100 times that required for high speed, and stemsfrom the energy-inefficient means of drop ejection. This involves therapid boiling of water to produce a vapor bubble which expels the ink.Water has a very high heat capacity, and must be superheated in thermalink jet applications. This leads to an efficiency of around 0.02%, fromelectricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size andcost. Piezoelectric crystals have a very small deflection at reasonabledrive voltages, and therefore require a large area for each nozzle.Also, each piezoelectric actuator must be connected to its drive circuiton a separate substrate. This is not a significant problem at thecurrent limit of around 300 nozzles per print head, but is a majorimpediment to the fabrication of pagewidth print heads with 19,200nozzles.

Ideally, the ink jet technologies used meet the stringent requirementsof in-camera digital color printing and other high quality, high speed,low cost printing applications. To meet the requirements of digitalphotography, new ink jet technologies have been created. The targetfeatures include:

low power (less than 10 Watts)

High-resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systemsdescribed below with differing levels of difficulty. Forty-fivedifferent ink jet technologies have been developed by the Assignee togive a wide range of choices for high volume manufacture. Thesetechnologies form part of separate applications assigned to the presentAssignee as set out in the table above under the heading CrossReferences to Related Applications.

The ink jet designs shown here are suitable for a wide range of digitalprinting systems, from battery powered one-time use digital cameras,through to desktop and network printers, and through to commercialprinting systems

For ease of manufacture using standard process equipment, the print headis designed to be a monolithic 0.5-micron CMOS chip with MEMS postprocessing. For color photographic applications, the print head is 100mm long, with a width which depends upon the ink jet type. The smallestprint head designed is IJ38, which is 0.35 mm wide, giving a chip areaof 35 square mm. The print heads each contain 19,200 nozzles plus dataand control circuitry.

Ink is supplied to the back of the print head by injection moldedplastic ink channels. The molding requires 50-micron features, which canbe created using a lithographically micro machined insert in a standardinjection-molding tool. Ink flows through holes etched through the waferto the nozzle chambers fabricated on the front surface of the wafer. Theprint head is connected to the camera circuitry by tape automatedbonding.

Tables of Drop-On-Demand Ink Jets

Eleven important characteristics of the fundamental operation ofindividual ink jet nozzles have been identified. These characteristicsare largely orthogonal, and so can be elucidated as an elevendimensional matrix. Most of the eleven axes of this matrix includeentries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains36.9 billion possible configurations of ink jet nozzle. While not all ofthe possible combinations result in a viable ink jet technology, manymillion configurations are viable. It is clearly impractical toelucidate all of the possible configurations. Instead, certain ink jettypes have been investigated in detail. These are designated IJ01 toIJ45 which matches the docket numbers in the table under the headingCROSS REFERENCES TO RELATED APPLICATIONS.

Other ink jet configurations can readily be derived from theseforty-five examples by substituting alternative configurations along oneor more of the 11 axes. Most of the IJ01 to IJ45 examples can be madeinto ink jet print heads with characteristics superior to any currentlyavailable ink jet technology.

Where there are prior art examples known to the inventor, one or more ofthese examples are listed in the examples column of the tables below.The IJ01 to IJ45 series are also listed in the examples column. In somecases, a printer may be listed more than once in a table, where itshares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Homeprinters, Office network printers, Short run digital printers,Commercial print systems, Fabric printers, Pocket printers, Internet WWWprinters, Video printers, Medical imaging, Wide format printers,Notebook PC printers, Fax machines, Industrial printing systems,Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrixis set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) DescriptionAdvantages Disadvantages Examples Thermal An electrothermal Large forceHigh power Canon Bubblejet bubble heater heats the ink to generated Inkcarrier limited 1979 Endo et al GB above boiling point, Simple to waterpatent 2,007,162 transferring significant construction Low efficiencyXerox heater-in- heat to the aqueous No moving parts High pit 1990Hawkins et ink. A bubble Fast operation temperatures al U.S. Pat. No.4,899,181 nucleates and quickly Small chip area required Hewlett-Packardforms, expelling the required for actuator High mechanical TIJ 1982Vaught et ink. stress al U.S. Pat. No. 4,490,728 The efficiency of theUnusual materials process is low, with required typically less thanLarge drive 0.05% of the electrical transistors energy being Cavitationcauses transformed into actuator failure kinetic energy of the Kogationreduces drop. bubble formation Large print heads are difficult tofabricate Piezoelectric A piezoelectric crystal Low power Very largearea Kyser et al U.S. Pat. No. such as lead consumption required foractuator 3,946,398 lanthanum zirconate Many ink types Difficult toZoltan U.S. Pat. No. (PZT) is electrically can be used integrate with3,683,212 activated, and either Fast operation electronics 1973 Stemmeexpands, shears, or High efficiency High voltage U.S. Pat. No. 3,747,120bends to apply drive transistors Epson Stylus pressure to the ink,required Tektronix ejecting drops. Full pagewidth IJ04 print headsimpractical due to actuator size Requires electrical poling in highfield strengths during manufacture Electro- An electric field is Lowpower Low maximum Seiko Epson, strictive used to activate consumptionstrain (approx. Usui et all JP electrostriction in Many ink types 0.01%)253401/96 relaxor materials such can be used Large area IJ04 as leadlanthanum Low thermal required for actuator zirconate titanate expansiondue to low strain (PLZT) or lead Electric field Response speed ismagnesium niobate strength required marginal (~10 μs) (PMN). (approx.3.5 V/μm) High voltage can be generated drive transistors withoutdifficulty required Does not require Full pagewidth electrical polingprint heads impractical due to actuator size Ferroelectric An electricfield is Low power Difficult to IJ04 used to induce a phase consumptionintegrate with transition between the Many ink types electronicsantiferroelectric (AFE) can be used Unusual materials and ferroelectric(FE) Fast operation such as PLZSnT are phase. Perovskite (<1 μs)required materials such as tin Relatively high Actuators requiremodified lead longitudinal strain a large area lanthanum zirconate Highefficiency titanate (PLZSnT) Electric field exhibit large strains ofstrength of around 3 V/μm up to 1% associated can be readily with theAFE to FE provided phase transition. Electrostatic Conductive plates areLow power Difficult to IJ02, IJ04 plates separated by a consumptionoperate electrostatic compressible or fluid Many ink types devices in andielectric (usually air). can be used aqueous Upon application of a Fastoperation environment voltage, the plates The electrostatic attract eachother and actuator will displace ink, causing normally need to be dropejection. The separated from the conductive plates may ink be in a combor Very large area honeycomb structure, required to achieve or stackedto increase high forces the surface area and High voltage therefore theforce. drive transistors may be required Full pagewidth print heads arenot competitive due to actuator size Electrostatic A strong electricfield Low current High voltage 1989 Saito et al, pull is applied to theink, consumption required U.S. Pat. No. 4,799,068 on ink whereupon Lowtemperature May be damaged 1989 Miura et al, electrostatic attraction bysparks due to air U.S. Pat. No. 4,810,954 accelerates the ink breakdownTone-jet towards the print Required field medium. strength increases asthe drop size decreases High voltage drive transistors requiredElectrostatic field attracts dust Permanent An electromagnet Low powerComplex IJ07, IJ10 magnet directly attracts a consumption fabricationelectro- permanent magnet, Many ink types Permanent magnetic displacingink and can be used magnetic material causing drop ejection. Fastoperation such as Neodymium Rare earth magnets High efficiency IronBoron (NdFeB) with a field strength Easy extension required. around 1Tesla can be from single nozzles High local used. Examples are: topagewidth print currents required Samarium Cobalt heads Copper (SaCo)and magnetic metalization should materials in the be used for longneodymium iron boron electromigration family (NdFeB, lifetime and lowNdDyFeBNb, resistivity NdDyFeB, etc) Pigmented inks are usuallyinfeasible Operating temperature limited to the Curie temperature(around 540 K) Soft A solenoid induced a Low power Complex IJ01, IJ05,IJ08, magnetic magnetic field in a soft consumption fabrication IJ10,IJ12, IJ14, core magnetic core or yoke Many ink types Materials notIJ15, IJ17 electro- fabricated from a can be used usually present in amagnetic ferrous material such Fast operation CMOS fab such as aselectroplated iron High efficiency NiFe, CoNiFe, or alloys such asCoNiFe Easy extension CoFe are required [1], CoFe, or NiFe from singlenozzles High local alloys. Typically, the to pagewidth print currentsrequired soft magnetic material heads Copper is in two parts, whichmetallisation should are normally held be used for long apart by aspring. electromigration When the solenoid is lifetime and low actuated,the two parts resistivity attract, displacing the Electroplating is ink.required High saturation flux density is required (2.0-2.1 T isachievable with CoNiFe [1]) Lorenz The Lorenz force Low power Force actsas a IJ06, IJ11, IJ13, force acting on a current consumption twistingmotion IJ16 carrying wire in a Many ink types Typically, only a magneticfield is can be used quarter of the utilized. Fast operation solenoidlength This allows the High efficiency provides force in a magneticfield to be Easy extension useful direction supplied externally to fromsingle nozzles High local the print head, for to pagewidth printcurrents required example with rare heads Copper earth permanentmetallisation should magnets. be used for long Only the currentelectromigration carrying wire need be lifetime and low fabricated onthe print- resistivity head, simplifying Pigmented inks materials areusually requirements. infeasible Magneto- The actuator uses the Many inktypes Force acts as a Fischenbeck, U.S. Pat. No. striction giantmagnetostrictive can be used twisting motion 4,032,929 effect ofmaterials Fast operation Unusual materials IJ25 such as Terfenol-D (anEasy extension such as Terfenol-D alloy of terbium, from single nozzlesare required dysprosium and iron to pagewidth print High local developedat the Naval heads currents required Ordnance Laboratory, High force isCopper hence Ter-Fe-NOL). available metallisation should For bestefficiency, the be used for long actuator should be pre- electromigration stressed to approx. 8 MPa. lifetime and low resistivityPre-stressing may be required Surface Ink under positive Low powerRequires Silverbrook, EP tension pressure is held in a consumptionsupplementary force 0771 658 A2 and reduction nozzle by surface Simpleto effect drop related patent tension. The surface constructionseparation applications tension of the ink is No unusual Requiresspecial reduced below the materials required in ink surfactants bubblethreshold, fabrication Speed may be causing the ink to High efficiencylimited by surfactant egress from the Easy extension properties nozzle.from single nozzles to pagewidth print heads Viscosity The ink viscosityis Simple Requires Silverbrook, EP reduction locally reduced toconstruction supplementary force 0771 658 A2 and select which drops areNo unusual to effect drop related patent to be ejected. A materialsrequired in separation applications viscosity reduction can fabricationRequires special be achieved Easy extension ink viscosityelectrothermally with from single nozzles properties most inks, butspecial to pagewidth print High speed is inks can be engineered headsdifficult to achieve for a 100:1 viscosity Requires reduction.oscillating ink pressure A high temperature difference (typically 80degrees) is required Acoustic An acoustic wave is Can operate Complexdrive 1993 Hadimioglu generated and without a nozzle circuitry et al,EUP 550,192 focussed upon the plate Complex 1993 Elrod et al, dropejection region. fabrication EUP 572,220 Low efficiency Poor control ofdrop position Poor control of drop volume Thermo- An actuator which Lowpower Efficient aqueous IJ03, IJ09, IJ17, elastic relies upondifferential consumption operation requires a IJ18, IJ19, IJ20, bendthermal expansion Many ink types thermal insulator on IJ21, IJ22, IJ23,actuator upon Joule heating is can be used the hot side IJ24, IJ27,IJ28, used. Simple planar Corrosion IJ29, IJ30, IJ31, fabricationprevention can be IJ32, IJ33, IJ34, Small chip area difficult IJ35,IJ36, IJ37, required for each Pigmented inks IJ38, IJ39, IJ40, actuatormay be infeasible, IJ41 Fast operation as pigment particles Highefficiency may jam the bend CMOS actuator compatible voltages andcurrents Standard MEMS processes can be used Easy extension from singlenozzles to pagewidth print heads High CTE A material with a very Highforce can be Requires special IJ09, IJ17, IJ18, thermo- high coefficientof generated material (e.g. PTFE) IJ20, IJ21, IJ22, elastic thermalexpansion Three methods of Requires a PTFE IJ23, IJ24, IJ27, actuator(CTE) such as PTFE deposition are deposition process, IJ28, IJ29, IJ30,polytetrafluoroethylene under development: which is not yet IJ31, IJ42,IJ43, (PTFE) is used. As chemical vapor standard in ULSI IJ44 high CTEmaterials deposition (CVD), fabs are usually non- spin coating, and PTFEdeposition conductive, a heater evaporation cannot be followedfabricated from a PTFE is a with high conductive material is candidatefor low temperature (above incorporated. A 50 μm dielectric constant350° C.) processing long PTFE bend insulation in ULSI Pigmented inksactuator with Very low power may be infeasible, polysilicon heater andconsumption as pigment particles 15 mW power input Many ink types mayjam the bend can provide 180 μN can be used actuator force and 10 μmSimple planar deflection. Actuator fabrication motions include: Smallchip area Bend required for each Push actuator Buckle Fast operationRotate High efficiency CMOS compatible voltages and currents Easyextension from single nozzles to pagewidth print heads Conductive Apolymer with a high High force can be Requires special IJ24 polymercoefficient of thermal generated materials thermo- expansion (such asVery low power development (High elastic PTFE) is doped with consumptionCTE conductive actuator conducting substances Many ink types polymer) toincrease its can be used Requires a PTFE conductivity to about Simpleplanar deposition process, 3 orders of magnitude fabrication which isnot yet below that of copper. Small chip area standard in ULSI Theconducting required for each fabs polymer expands actuator PTFEdeposition when resistively Fast operation cannot be followed heated.High efficiency with high Examples of CMOS temperature (above conductingdopants compatible voltages 350° C.) processing include: and currentsEvaporation and Carbon nanotubes Easy extension CVD deposition Metalfibers from single nozzles techniques cannot Conductive polymers topagewidth print be used such as doped heads Pigmented inks polythiophenemay be infeasible, Carbon granules as pigment particles may jam the bendactuator Shape A shape memory alloy High force is Fatigue limits IJ26memory such as TiNi (also available (stresses maximum number alloy knownas Nitinol - of hundreds of of cycles Nickel Titanium alloy MPa) Lowstrain (1%) developed at the Naval Large strain is is required to extendOrdnance Laboratory) available (more than fatigue resistance isthermally switched 3%) Cycle rate limited between its weak Highcorrosion by heat removal martensitic state and resistance Requiresunusual its high stiffness Simple materials (TiNi) austenic state. Theconstruction The latent heat of shape of the actuator Easy extensiontransformation must in its martensitic state from single nozzles beprovided is deformed relative to to pagewidth print High current theaustenitic shape. heads operation The shape change Low voltage Requirespre- causes ejection of a operation stressing to distort drop. themartensitic state Linear Linear magnetic Linear Magnetic Requiresunusual IJ12 Magnetic actuators include the actuators can besemiconductor Actuator Linear Induction constructed with materials suchas Actuator (LIA), Linear high thrust, long soft magnetic alloysPermanent Magnet travel, and high (e.g. CoNiFe) Synchronous Actuatorefficiency using Some varieties (LPMSA), Linear planar also requireReluctance semiconductor permanent magnetic Synchronous Actuatorfabrication materials such as (LRSA), Linear techniques Neodymium ironSwitched Reluctance Long actuator boron (NdFeB) Actuator (LSRA), andtravel is available Requires complex the Linear Stepper Medium force ismulti-phase drive Actuator (LSA). available circuitry Low voltage Highcurrent operation operation

BASIC OPERATION MODE Description Advantages Disadvantages ExamplesActuator This is the simplest Simple operation Drop repetition Thermalink jet directly mode of operation: the No external fields rate isusually Piezoelectric ink pushes ink actuator directly required limitedto around 10 kHz. jet supplies sufficient Satellite drops can However,this IJ01, IJ02, IJ03, kinetic energy to expel be avoided if drop is notfundamental IJ04, IJ05, IJ06, the drop. The drop velocity is less thanto the method, but is IJ07, IJ09, IJ11, must have a sufficient 4 m/srelated to the refill IJ12, IJ14, IJ16, velocity to overcome Can beefficient, method normally IJ20, IJ22, IJ23, the surface tension.depending upon the used IJ24, IJ25, IJ26, actuator used All of the dropIJ27, IJ28, IJ29, kinetic energy must IJ30, IJ31, IJ32, be provided bythe IJ33, IJ34, IJ35, actuator IJ36, IJ37, IJ38, Satellite drops IJ39,IJ40, IJ41, usually form if drop IJ42, IJ43, IJ44 velocity is greaterthan 4.5 m/s Proximity The drops to be Very simple print Requires closeSilverbrook, EP printed are selected by head fabrication can proximitybetween 0771 658 A2 and some manner (e.g. be used the print head andrelated patent thermally induced The drop the print media orapplications surface tension selection means transfer roller reductionof does not need to May require two pressurized ink). provide the energyprint heads printing Selected drops are required to separate alternaterows of the separated from the ink the drop from the image in the nozzleby nozzle Monolithic color contact with the print print heads are mediumor a transfer difficult roller. Electrostatic The drops to be Verysimple print Requires very Silverbrook, EP pull printed are selected byhead fabrication can high electrostatic 0771 658 A2 and on ink somemanner (e.g. be used field related patent thermally induced The dropElectrostatic field applications surface tension selection means forsmall nozzle Tone-Jet reduction of does not need to sizes is above airpressurized ink). provide the energy breakdown Selected drops arerequired to separate Electrostatic field separated from the ink the dropfrom the may attract dust in the nozzle by a nozzle strong electricfield. Magnetic The drops to be Very simple print Requires Silverbrook,EP pull on ink printed are selected by head fabrication can magnetic ink0771 658 A2 and some manner (e.g. be used Ink colors other relatedpatent thermally induced The drop than black are applications surfacetension selection means difficult reduction of does not need to Requiresvery pressurized ink). provide the energy high magnetic fields Selecteddrops are required to separate separated from the ink the drop from thein the nozzle by a nozzle strong magnetic field acting on the magneticink. Shutter The actuator moves a High speed (>50 kHz) Moving parts areIJ13, IJ17, IJ21 shutter to block ink operation can required flow to thenozzle. be achieved due to Requires ink The ink pressure is reducedrefill time pressure modulator pulsed at a multiple of Drop timing canFriction and wear the drop ejection be very accurate must be consideredfrequency. The actuator Stiction is energy can be very possible lowShuttered The actuator moves a Actuators with Moving parts are IJ08,IJ15, IJ18, grill shutter to block ink small travel can be required IJ19flow through a grill to used Requires ink the nozzle. The shutterActuators with pressure modulator movement need only small force can beFriction and wear be equal to the width used must be considered of thegrill holes. High speed (>50 kHz) Stiction is operation can possible beachieved Pulsed A pulsed magnetic Extremely low Requires an IJ10magnetic field attracts an ‘ink energy operation is external pulsed pullon ink pusher’ at the drop possible magnetic field pusher ejectionfrequency. An No heat Requires special actuator controls a dissipationmaterials for both catch, which prevents problems the actuator and thethe ink pusher from ink pusher moving when a drop is Complex not to beejected. construction

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description AdvantagesDisadvantages Examples None The actuator directly Simplicity of Dropejection Most ink jets, fires the ink drop, and construction energy mustbe including there is no external Simplicity of supplied bypiezoelectric and field or other operation individual nozzle thermalbubble. mechanism required. Small physical actuator IJ01, IJ02, IJ03,size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24,IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36,IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The inkpressure Oscillating ink Requires external Silverbrook, EP inkoscillates, providing pressure can ink pressure 0771 658 A2 and pressuremuch of the drop provide a refill oscillator related patent (includingejection energy. The pulse, allowing Ink pressure applications acousticactuator selects which higher operating phase and amplitude IJ08, IJ13,IJ15, stimulation) drops are to be fired speed must be carefully IJ17,IJ18, IJ19, by selectively The actuators may controlled IJ21 blocking orenabling operate with much Acoustic nozzles. The ink lower energyreflections in the ink pressure oscillation Acoustic lenses chamber mustbe may be achieved by can be used to focus designed for vibrating theprint the sound on the head, or preferably by nozzles an actuator in theink supply. Media The print head is Low power Precision Silverbrook, EPproximity placed in close High accuracy assembly required 0771 658 A2and proximity to the print Simple print head Paper fibers may relatedpatent medium. Selected construction cause problems applications dropsprotrude from Cannot print on the print head further rough substratesthan unselected drops, and contact the print medium. The drop soaks intothe medium fast enough to cause drop separation. Transfer Drops areprinted to a High accuracy Bulky Silverbrook, EP roller transfer rollerinstead Wide range of Expensive 0771 658 A2 and of straight to the printprint substrates can Complex related patent medium. A transfer be usedconstruction applications roller can also be used Ink can be driedTektronix hot for proximity drop on the transfer roller meltpiezoelectric separation. ink jet Any of the IJ series Electrostatic Anelectric field is Low power Field strength Silverbrook, EP used toaccelerate Simple print head required for 0771 658 A2 and selected dropstowards construction separation of small related patent the printmedium. drops is near or applications above air Tone-Jet breakdownDirect A magnetic field is Low power Requires Silverbrook, EP magneticused to accelerate Simple print head magnetic ink 0771 658 A2 and fieldselected drops of construction Requires strong related patent magneticink towards magnetic field applications the print medium. Cross Theprint head is Does not require Requires external IJ06, IJ16 magneticplaced in a constant magnetic materials magnet field magnetic field. Theto be integrated in Current densities Lorenz force in a the print headmay be high, current carrying wire manufacturing resulting in is used tomove the process electromigration actuator. problems Pulsed A pulsedmagnetic Very low power Complex print IJ10 magnetic field is used tooperation is possible head construction field cyclically attract a Smallprint head Magnetic paddle, which pushes size materials required in onthe ink. A small print head actuator moves a catch, which selectivelyprevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description AdvantagesDisadvantages Examples None No actuator Operational Many actuatorThermal Bubble mechanical simplicity mechanisms have Ink jetamplification is used. insufficient travel, IJ01, IJ02, IJ06, Theactuator directly or insufficient force, IJ07, IJ16, IJ25, drives thedrop to efficiently drive IJ26 ejection process. the drop ejectionprocess Differential An actuator material Provides greater High stressesare Piezoelectric expansion expands more on one travel in a reducedinvolved IJ03, IJ09, IJ17, bend side than on the other. print head areaCare must be IJ18, IJ19, IJ20, actuator The expansion may be taken thatthe IJ21, IJ22, IJ23, thermal, piezoelectric, materials do not IJ24,IJ27, IJ29, magnetostrictive, or delaminate IJ30, IJ31, IJ32, othermechanism. The Residual bend IJ33, IJ34, IJ35, bend actuator convertsresulting from high IJ36, IJ37, IJ38, a high force low traveltemperature or high IJ39, IJ42, IJ43, actuator mechanism to stressduring IJ44 high travel, lower formation force mechanism. Transient Atrilayer bend Very good High stresses are IJ40, IJ41 bend actuator wherethe two temperature stability involved actuator outside layers are Highspeed, as a Care must be identical. This cancels new drop can be takenthat the bend due to ambient fired before heat materials do nottemperature and dissipates delaminate residual stress. The Cancelsresidual actuator only responds stress of formation to transient heatingof one side or the other. Reverse The actuator loads a Better couplingto Fabrication IJ05, IJ11 spring spring. When the the ink complexityactuator is turned off, High stress in the the spring releases. springThis can reverse the force/distance curve of the actuator to make itcompatible with the force/time requirements of the drop ejection.Actuator A series of thin Increased travel Increased Some stackactuators are stacked. Reduced drive fabrication piezoelectric ink jetsThis can be voltage complexity IJ04 appropriate where Increasedactuators require high possibility of short electric field strength,circuits due to such as electrostatic pinholes and piezoelectricactuators. Multiple Multiple smaller Increases the Actuator forces IJ12,IJ13, IJ18, actuators actuators are used force available from may notadd IJ20, IJ22, IJ28, simultaneously to an actuator linearly, reducingIJ42, IJ43 move the ink. Each Multiple actuators efficiency actuatorneed provide can be positioned to only a portion of the control ink flowforce required. accurately Linear A linear spring is used Matches lowRequires print IJ15 Spring to transform a motion travel actuator withhead area for the with small travel and higher travel spring high forceinto a requirements longer travel, lower Non-contact force motion.method of motion transformation Coiled A bend actuator is Increasestravel Generally IJ17, IJ21, IJ34, actuator coiled to provide Reduceschip area restricted to planar IJ35 greater travel in a Planarimplementations reduced chip area. implementations are due to extremerelatively easy to fabrication fabricate. difficulty in otherorientations. Flexure A bend actuator has a Simple means of Care must beIJ10, IJ19, IJ33 bend small region near the increasing travel of takennot to exceed actuator fixture point, which a bend actuator the elasticlimit in flexes much more the flexure area readily than the Stressdistribution remainder of the is very uneven actuator. The actuatorDifficult to flexing is effectively accurately model converted from anwith finite element even coiling to an analysis angular bend, resultingin greater travel of the actuator tip. Catch The actuator controls aVery low actuator Complex IJ10 small catch. The catch energyconstruction either enables or Very small Requires external disablesmovement of actuator size force an ink pusher that is Unsuitable forcontrolled in a bulk pigmented inks manner. Gears Gears can be used toLow force, low Moving parts are IJ13 increase travel at the travelactuators can required expense of duration. be used Several actuatorCircular gears, rack Can be fabricated cycles are required and pinion,ratchets, using standard More complex and other gearing surface MEMSdrive electronics methods can be used. processes Complex constructionFriction, friction, and wear are possible Buckle A buckle plate can beVery fast Must stay within S. Hirata et al, plate used to change a slowmovement elastic limits of the “An Ink-jet Head actuator into a fastachievable materials for long Using Diaphragm motion. It can also devicelife Microactuator”, convert a high force, High stresses Proc. IEEEMEMS, low travel actuator involved February 1996, pp 418-423. into ahigh travel, Generally high IJ18, IJ27 medium force motion. powerrequirement Tapered A tapered magnetic Linearizes the Complex IJ14magnetic pole can increase magnetic construction pole travel at theexpense force/distance curve of force. Lever A lever and fulcrum isMatches low High stress IJ32, IJ36, IJ37 used to transform a travelactuator with around the fulcrum motion with small higher travel traveland high force requirements into a motion with Fulcrum area has longertravel and no linear movement, lower force. The lever and can be usedfor can also reverse the a fluid seal direction of travel. Rotary Theactuator is High mechanical Complex IJ28 impeller connected to a rotaryadvantage construction impeller. A small The ratio of force Unsuitablefor angular deflection of to travel of the pigmented inks the actuatorresults in actuator can be a rotation of the matched to the impellervanes, which nozzle requirements push the ink against by varying thestationary vanes and number of impeller out of the nozzle. vanesAcoustic A refractive or No moving parts Large area 1993 Hadimioglu lensdiffractive (e.g. zone required et al, EUP 550,192 plate) acoustic lensis Only relevant for 1993 Elrod et al, used to concentrate acoustic inkjets EUP 572,220 sound waves. Sharp A sharp point is used SimpleDifficult to Tone-jet conductive to concentrate an constructionfabricate using point electrostatic field. standard VLSI processes for asurface ejecting ink- jet Only relevant for electrostatic ink jets

ACTUATOR MOTION Description Advantages Disadvantages Examples Volume Thevolume of the Simple High energy is Hewlett-Packard expansion actuatorchanges, construction in the typically required to Thermal Ink jetpushing the ink in all case of thermal ink achieve volume CanonBubblejet directions. jet expansion. This leads to thermal stress,cavitation, and kogation in thermal ink jet implementations Linear, Theactuator moves in Efficient coupling High fabrication IJ01, IJ02, IJ04,normal to a direction normal to to ink drops ejected complexity may beIJ07, IJ11, IJ14 chip the print head surface. normal to the required toachieve surface The nozzle is typically surface perpendicular in theline of motion movement. Parallel to The actuator moves Suitable forFabrication IJ12, IJ13, IJ15, chip parallel to the print planarfabrication complexity IJ33,, IJ34, IJ35, surface head surface. DropFriction IJ36 ejection may still be Stiction normal to the surface.Membrane An actuator with a The effective area Fabrication 1982 Howkinspush high force but small of the actuator complexity U.S. Pat. No.4,459,601 area is used to push a becomes the Actuator size stiffmembrane that is membrane area Difficulty of in contact with the ink.integration in a VLSI process Rotary The actuator causes Rotary leversmay Device IJ05, IJ08, IJ13, the rotation of some be used to increasecomplexity IJ28 element, such a grill or travel May have frictionimpeller Small chip area at a pivot point requirements Bend The actuatorbends A very small Requires the 1970 Kyser et al when energized. Thischange in actuator to be made U.S. Pat. No. 3,946,398 may be due todimensions can be from at least two 1973 Stemme differential thermalconverted to a large distinct layers, or to U.S. Pat. No. 3,747,120expansion, motion. have a thermal IJ03, IJ09, IJ10, piezoelectricdifference across the IJ19, IJ23, IJ24, expansion, actuator IJ25, IJ29,IJ30, magnetostriction, or IJ31, IJ33, IJ34, other form of relative IJ35dimensional change. Swivel The actuator swivels Allows operationInefficient IJ06 around a central pivot. where the net linear couplingto the ink This motion is suitable force on the paddle motion wherethere are is zero opposite forces Small chip area applied to oppositerequirements sides of the paddle, e.g. Lorenz force. Straighten Theactuator is Can be used with Requires careful IJ26, IJ32 normally bent,and shape memory balance of stresses straightens when alloys where theto ensure that the energized. austenic phase is quiescent bend is planaraccurate Double The actuator bends in One actuator can Difficult to makeIJ36, IJ37, IJ38 bend one direction when be used to power the dropsejected by one element is two nozzles. both bend directions energized,and bends Reduced chip identical. the other way when size. A smallefficiency another element is Not sensitive to loss compared toenergized. ambient temperature equivalent single bend actuators. ShearEnergizing the Can increase the Not readily 1985 Fishbeck actuatorcauses a shear effective travel of applicable to other U.S. Pat. No.4,584,590 motion in the actuator piezoelectric actuator material.actuators mechanisms Radial The actuator squeezes Relatively easy toHigh force 1970 Zoltan U.S. Pat. No. constriction an ink reservoir,fabricate single required 3,683,212 forcing ink from a nozzles fromglass Inefficient constricted nozzle. tubing as Difficult to macroscopicintegrate with VLSI structures processes Coil/ A coiled actuator Easy tofabricate Difficult to IJ17, IJ21, IJ34, uncoil uncoils or coils more asa planar VLSI fabricate for non- IJ35 tightly. The motion of processplanar devices the free end of the Small area Poor out-of-plane actuatorejects the ink. required, therefore stiffness low cost Bow The actuatorbows (or Can increase the Maximum travel IJ16, IJ18, IJ27 buckles) inthe middle speed of travel is constrained when energized. MechanicallyHigh force rigid required Push-Pull Two actuators control The structureis Not readily IJ18 a shutter. One actuator pinned at both ends,suitable for ink jets pulls the shutter, and so has a high out-of- whichdirectly push the other pushes it. plane rigidity the ink Curl A set ofactuators curl Good fluid flow Design IJ20, IJ42 inwards inwards toreduce the to the region behind complexity volume of ink that theactuator they enclose. increases efficiency Curl A set of actuators curlRelatively simple Relatively large IJ43 outwards outwards, pressurizingconstruction chip area ink in a chamber surrounding the actuators, andexpelling ink from a nozzle in the chamber. Iris Multiple vanes encloseHigh efficiency High fabrication IJ22 a volume of ink. These Small chiparea complexity simultaneously rotate, Not suitable for reducing thevolume pigmented inks between the vanes. Acoustic The actuator vibratesThe actuator can Large area 1993 Hadimioglu vibration at a highfrequency. be physically distant required for et al, EUP 550,192 fromthe ink efficient operation 1993 Elrod et al, at useful frequencies EUP572,220 Acoustic coupling and crosstalk Complex drive circuitry Poorcontrol of drop volume and position None In various ink jet No movingparts Various other Silverbrook, EP designs the actuator tradeoffs are0771 658 A2 and does not move. required to related patent eliminatemoving applications parts Tone-jet

NOZZLE REFILL METHOD Description Advantages Disadvantages ExamplesSurface This is the normal way Fabrication Low speed Thermal ink jettension that ink jets are simplicity Surface tension Piezoelectric inkrefilled. After the Operational force relatively jet actuator isenergized, simplicity small compared to IJ01-IJ07, IJ10-IJ14, ittypically returns actuator force IJ16, IJ20, rapidly to its normal Longrefill time IJ22-IJ45 position. This rapid usually dominates returnsucks in air the total repetition through the nozzle rate opening. Theink surface tension at the nozzle then exerts a small force restoringthe meniscus to a minimum area. This force refills the nozzle. ShutteredInk to the nozzle High speed Requires common IJ08, IJ13, IJ15,oscillating chamber is provided at Low actuator ink pressure IJ17, IJ18,IJ19, ink a pressure that energy, as the oscillator IJ21 pressureoscillates at twice the actuator need only May not be drop ejection openor close the suitable for frequency. When a shutter, instead ofpigmented inks drop is to be ejected, ejecting the ink drop the shutteris opened for 3 half cycles: drop ejection, actuator return, and refill.The shutter is then closed to prevent the nozzle chamber emptying duringthe next negative pressure cycle. Refill After the main High speed, asthe Requires two IJ09 actuator actuator has ejected a nozzle is activelyindependent drop a second (refill) refilled actuators per nozzleactuator is energized. The refill actuator pushes ink into the nozzlechamber. The refill actuator returns slowly, to prevent its return fromemptying the chamber again. Positive The ink is held a slight Highrefill rate, Surface spill must Silverbrook, EP ink positive pressure.therefore a high be prevented 0771 658 A2 and pressure After the inkdrop is drop repetition rate Highly related patent ejected, the nozzleis possible hydrophobic print applications chamber fills quickly headsurfaces are Alternative for:, as surface tension and requiredIJ01-IJ07, IJ10-IJ14, ink pressure both IJ16, IJ20, operate to refillthe IJ22-IJ45 nozzle.

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description AdvantagesDisadvantages Examples Long inlet The ink inlet channel Designsimplicity Restricts refill Thermal ink jet channel to the nozzlechamber Operational rate Piezoelectric ink is made long and simplicityMay result in a jet relatively narrow, Reduces crosstalk relativelylarge chip IJ42, IJ43 relying on viscous area drag to reduce inlet Onlypartially back-flow. effective Positive The ink is under a Dropselection Requires a Silverbrook, EP ink positive pressure, so andseparation method (such as a 0771 658 A2 and pressure that in thequiescent forces can be nozzle rim or related patent state some of theink reduced effective applications drop already protrudes Fast refilltime hydrophobizing, or Possible operation from the nozzle. both) toprevent of the following: This reduces the flooding of the IJ01-IJ07,IJ09-IJ12, pressure in the nozzle ejection surface of IJ14, IJ16,chamber which is the print head. IJ20, IJ22,, IJ23-IJ34, required toeject a IJ36-IJ41, certain volume of ink. IJ44 The reduction in chamberpressure results in a reduction in ink pushed out through the inlet.Baffle One or more baffles The refill rate is Design HP Thermal Ink areplaced in the inlet not as restricted as complexity Jet ink flow. Whenthe the long inlet May increase Tektronix actuator is energized, method.fabrication piezoelectric ink jet the rapid ink Reduces crosstalkcomplexity (e.g. movement creates Tektronix hot melt eddies whichrestrict Piezoelectric print the flow through the heads). inlet. Theslower refill process is unrestricted, and does not result in eddies.Flexible In this method recently Significantly Not applicable to Canonflap disclosed by Canon, reduces back-flow most ink jet restricts theexpanding actuator for edge-shooter configurations inlet (bubble) pusheson a thermal ink jet Increased flexible flap that devices fabricationrestricts the inlet. complexity Inelastic deformation of polymer flapresults in creep over extended use Inlet filter A filter is locatedAdditional Restricts refill IJ04, IJ12, IJ24, between the ink inletadvantage of ink rate IJ27, IJ29, IJ30 and the nozzle filtration Mayresult in chamber. The filter Ink filter may be complex has a multitudeof fabricated with no construction small holes or slots, additionalprocess restricting ink flow. steps The filter also removes particleswhich may block the nozzle. Small inlet The ink inlet channel Designsimplicity Restricts refill IJ02, IJ37, IJ44 compared to the nozzlechamber rate to nozzle has a substantially May result in a smaller crosssection relatively large chip than that of the nozzle, area resulting ineasier ink Only partially egress out of the effective nozzle than out ofthe inlet. Inlet A secondary actuator Increases speed of Requiresseparate IJ09 shutter controls the position the ink-jet print refillactuator and of a shutter, closing head operation drive circuit off theink inlet when the main actuator is energized. The inlet is The methodavoids the Back-flow Requires careful IJ01, IJ03, IJ05, located problemof inlet back- problem is design to minimize IJ06, IJ07, IJ10, behindthe flow by arranging the eliminated the negative IJ11, IJ14, IJ16, ink-ink-pushing surface of pressure behind the IJ22, IJ23, IJ25, pushing theactuator between paddle IJ28, IJ31, IJ32, surface the inlet and theIJ33, IJ34, IJ35, nozzle. IJ36, IJ39, IJ40, IJ41 Part of the Theactuator and a Significant Small increase in IJ07, IJ20, IJ26, actuatorwall of the ink reductions in back- fabrication IJ38 moves to chamberare arranged flow can be complexity shut off so that the motion ofachieved the inlet the actuator closes off Compact designs the inlet.possible Nozzle In some configurations Ink back-flow None related toSilverbrook, EP actuator of ink jet, there is no problem is inkback-flow on 0771 658 A2 and does not expansion or eliminated actuationrelated patent result in movement of an applications ink back- actuatorwhich may Valve-jet flow cause ink back-flow Tone-jet through the inlet.

NOZZLE CLEARING METHOD Description Advantages Disadvantages ExamplesNormal All of the nozzles are No added May not be Most ink jet nozzlefired periodically, complexity on the sufficient to systems firingbefore the ink has a print head displace dried ink IJ01, IJ02, IJ03,chance to dry. When IJ04, IJ05, IJ06, not in use the nozzles IJ07, IJ09,IJ10, are sealed (capped) IJ11, IJ12, IJ14, against air. IJ16, IJ20,IJ22, The nozzle firing is IJ23, IJ24, IJ25, usually performed IJ26,IJ27, IJ28, during a special IJ29, IJ30, IJ31, clearing cycle, afterIJ32, IJ33, IJ34, first moving the print IJ36, IJ37, IJ38, head to acleaning IJ39, IJ40,, IJ41, station. IJ42, IJ43, IJ44,, IJ45 Extra Insystems which heat Can be highly Requires higher Silverbrook, EP powerto the ink, but do not boil effective if the drive voltage for 0771 658A2 and ink heater it under normal heater is adjacent to clearing relatedpatent situations, nozzle the nozzle May require applications clearingcan be larger drive achieved by over- transistors powering the heaterand boiling ink at the nozzle. Rapid The actuator is fired in Does notrequire Effectiveness May be used succession rapid succession. In extradrive circuits depends with: IJ01, IJ02, of some configurations, on theprint head substantially upon IJ03, IJ04, IJ05, actuator this may causeheat Can be readily the configuration of IJ06, IJ07, IJ09, pulsesbuild-up at the nozzle controlled and the ink jet nozzle IJ10, IJ11,IJ14, which boils the ink, initiated by digital IJ16, IJ20, IJ22,clearing the nozzle. In logic IJ23, IJ24, IJ25, other situations, it mayIJ27, IJ28, IJ29, cause sufficient IJ30, IJ31, IJ32, vibrations todislodge IJ33, IJ34, IJ36, clogged nozzles. IJ37, IJ38, IJ39, IJ40,IJ41, IJ42, IJ43, IJ44, IJ45 Extra Where an actuator is A simplesolution Not suitable May be used power to not normally driven to whereapplicable where there is a with: IJ03, IJ09, ink the limit of itsmotion, hard limit to IJ16, IJ20, IJ23, pushing nozzle clearing may beactuator movement IJ24, IJ25, IJ27, actuator assisted by providing IJ29,IJ30, IJ31, an enhanced drive IJ32, IJ39, IJ40, signal to the actuator.IJ41, IJ42, IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is A highnozzle High IJ08, IJ13, IJ15, resonance applied to the ink clearingcapability implementation cost IJ17, IJ18, IJ19, chamber. This wave iscan be achieved if system does not IJ21 of an appropriate May be alreadyinclude an amplitude and implemented at very acoustic actuator frequencyto cause low cost in systems sufficient force at the which alreadynozzle to clear include acoustic blockages. This is actuators easiest toachieve if the ultrasonic wave is at a resonant frequency of the inkcavity. Nozzle A microfabricated Can clear severely AccurateSilverbrook, EP clearing plate is pushed against clogged nozzlesmechanical 0771 658 A2 and plate the nozzles. The plate alignment isrelated patent has a post for every required applications nozzle. A postmoves Moving parts are through each nozzle, required displacing driedink. There is risk of damage to the nozzles Accurate fabrication isrequired Ink The pressure of the ink May be effective Requires pressureMay be used with pressure is temporarily where other pump or other allIJ series ink jets pulse increased so that ink methods cannot bepressure actuator streams from all of the used Expensive nozzles. Thismay be Wasteful of ink used in conjunction with actuator energizing.Print head A flexible ‘blade’ is Effective for Difficult to use if Manyink jet wiper wiped across the print planar print head print headsurface is systems head surface. The surfaces non-planar or very bladeis usually Low cost fragile fabricated from a Requires flexible polymer,e.g. mechanical parts rubber or synthetic Blade can wear elastomer. outin high volume print systems Separate A separate heater is Can beeffective Fabrication Can be used with ink boiling provided at thenozzle where other nozzle complexity many IJ series ink heater althoughthe normal clearing methods jets drop ejection cannot be used mechanismdoes not Can be require it. The heaters implemented at no do not requireadditional cost in individual drive some ink jet circuits, as manyconfigurations nozzles can be cleared simultaneously, and no imaging isrequired.

NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages ExamplesElectroformed A nozzle plate is Fabrication High Hewlett Packard nickelseparately fabricated simplicity temperatures and Thermal Ink jet fromelectroformed pressures are nickel, and bonded to required to bond theprint head chip. nozzle plate Minimum thickness constraints Differentialthermal expansion Laser Individual nozzle No masks Each hole must beCanon Bubblejet ablated or holes are ablated by an required individuallyformed 1988 Sercel et al., drilled intense UV laser in a Can be quitefast Special SPIE, Vol. 998 polymer nozzle plate, which is Some controlequipment required Excimer Beam typically a polymer over nozzle profileSlow where there Applications, pp. such as polyimide or is possible aremany thousands 76-83 polysulphone Equipment of nozzles per print 1993Watanabe et required is relatively head al., U.S. Pat. No. 5,208,604 lowcost May produce thin burrs at exit holes Silicon A separate nozzle Highaccuracy is Two part K. Bean, IEEE micromachined plate is attainableconstruction Transactions on micromachined from High cost ElectronDevices, single crystal silicon, Requires Vol. ED-25, No. 10, and bondedto the precision alignment 1978, pp 1185-1195 print head wafer. Nozzlesmay be Xerox 1990 clogged by adhesive Hawkins et al., U.S. Pat. No.4,899,181 Glass Fine glass capillaries No expensive Very small nozzle1970 Zoltan U.S. Pat. No. capillaries are drawn from glass equipmentrequired sizes are difficult to 3,683,212 tubing. This method Simple tomake form has been used for single nozzles Not suited for makingindividual mass production nozzles, but is difficult to use for bulkmanufacturing of print heads with thousands of nozzles. Monolithic, Thenozzle plate is High accuracy Requires Silverbrook, EP surface depositedas a layer (<1 μm) sacrificial layer 0771 658 A2 and micromachined usingstandard VLSI Monolithic under the nozzle related patent using VLSIdeposition techniques. Low cost plate to form the applicationslithographic Nozzles are etched in Existing nozzle chamber IJ01, IJ02,IJ04, processes the nozzle plate using processes can be Surface may beIJ11, IJ12, IJ17, VLSI lithography and used fragile to the touch IJ18,IJ20, IJ22, etching. IJ24, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33,IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Monolithic,The nozzle plate is a High accuracy Requires long IJ03, IJ05, IJ06,etched buried etch stop in the (<1 μm) etch times IJ07, IJ08, IJ09,through wafer. Nozzle Monolithic Requires a IJ10, IJ13, IJ14, substratechambers are etched in Low cost support wafer IJ15, IJ16, IJ19, thefront of the wafer, No differential IJ21, IJ23, IJ25, and the wafer isexpansion IJ26 thinned from the back side. Nozzles are then etched inthe etch stop layer. No nozzle Various methods have No nozzles toDifficult to Ricoh 1995 plate been tried to eliminate become cloggedcontrol drop Sekiya et al U.S. Pat. No. the nozzles entirely, toposition accurately 5,412,413 prevent nozzle Crosstalk 1993 Hadimiogluclogging. These problems et al EUP 550,192 include thermal bubble 1993Elrod et al mechanisms and EUP 572,220 acoustic lens mechanisms TroughEach drop ejector has Reduced Drop firing IJ35 a trough throughmanufacturing direction is sensitive which a paddle moves. complexity towicking. There is no nozzle Monolithic plate. Nozzle slit Theelimination of No nozzles to Difficult to 1989 Saito et al instead ofnozzle holes and become clogged control drop U.S. Pat. No. 4,799,068individual replacement by a slit position accurately nozzlesencompassing many Crosstalk actuator positions problems reduces nozzleclogging, but increases crosstalk due to ink surface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages ExamplesEdge Ink flow is along the Simple Nozzles limited to Canon Bubblejet(‘edge surface of the chip, construction edge 1979 Endo et al GBshooter’) and ink drops are No silicon etching High resolution is patent2,007,162 ejected from the chip required difficult Xerox heater-in-edge. Good heat sinking Fast color pit 1990 Hawkins et via substrateprinting requires al U.S. Pat. No. 4,899,181 Mechanically one print headper Tone-jet strong color Ease of chip handing Surface Ink flow is alongthe No bulk silicon Maximum ink Hewlett-Packard (‘roof surface of thechip, etching required flow is severely TIJ 1982 Vaught et shooter’) andink drops are Silicon can make restricted al U.S. Pat. No. 4,490,728ejected from the chip an effective heat IJ02, IJ11, IJ12, surface,normal to the sink IJ20, IJ22 plane of the chip. Mechanical strengthThrough Ink flow is through the High ink flow Requires bulk Silverbrook,EP chip, chip, and ink drops are Suitable for silicon etching 0771 658A2 and forward ejected from the front pagewidth print related patent(‘up surface of the chip. heads applications shooter’) High nozzle IJ04,IJ17, IJ18, packing density IJ24, IJ27-IJ45 therefore low manufacturingcost Through Ink flow is through the High ink flow Requires wafer IJ01,IJ03, IJ05, chip, chip, and ink drops are Suitable for thinning IJ06,IJ07, IJ08, reverse ejected from the rear pagewidth print Requiresspecial IJ09, IJ10, IJ13, (‘down surface of the chip. heads handlingduring IJ14, IJ15, IJ16, shooter’) High nozzle manufacture IJ19, IJ21,IJ23, packing density IJ25, IJ26 therefore low manufacturing costThrough Ink flow is through the Suitable for Pagewidth print EpsonStylus actuator actuator, which is not piezoelectric print heads requireTektronix hot fabricated as part of heads several thousand meltpiezoelectric the same substrate as connections to drive ink jets thedrive transistors. circuits Cannot be manufactured in standard CMOS fabsComplex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Waterbased ink which Environmentally Slow drying Most existing ink dyetypically contains: friendly Corrosive jets water, dye, surfactant, Noodor Bleeds on paper All IJ series ink humectant, and May jets biocide.strikethrough Silverbrook, EP Modern ink dyes have Cockles paper 0771658 A2 and high water-fastness, related patent light fastnessapplications Aqueous, Water based ink which Environmentally Slow dryingIJ02, IJ04, IJ21, pigment typically contains: friendly Corrosive IJ26,IJ27, IJ30 water, pigment, No odor Pigment may clog Silverbrook, EPsurfactant, humectant, Reduced bleed nozzles 0771 658 A2 and andbiocide. Reduced wicking Pigment may clog related patent Pigments havean Reduced actuator applications advantage in reduced strikethroughmechanisms Piezoelectric ink- bleed, wicking and Cockles paper jetsstrikethrough. Thermal ink jets (with significant restrictions) MethylMEK is a highly Very fast drying Odorous All IJ series ink Ethylvolatile solvent used Prints on various Flammable jets Ketone forindustrial printing substrates such as (MEK) on difficult surfacesmetals and plastics such as aluminum cans. Alcohol Alcohol based inksFast drying Slight odor All IJ series ink (ethanol, can be used wherethe Operates at sub- Flammable jets 2-butanol, printer must operate atfreezing and temperatures below temperatures others) the freezing pointof Reduced paper water. An example of cockle this is in-camera Low costconsumer photographic printing. Phase The ink is solid at No dryingtime- High viscosity Tektronix hot change room temperature, and inkinstantly freezes Printed ink melt piezoelectric (hot melt) is melted inthe print on the print medium typically has a ink jets head beforejetting. Almost any print ‘waxy’ feel 1989 Nowak U.S. Pat. No. Hot meltinks are medium can be used Printed pages may 4,820,346 usually waxbased, No paper cockle ‘block’ All IJ series ink with a melting pointoccurs Ink temperature jets around 80° C. After No wicking may be abovethe jetting the ink freezes occurs curie point of almost instantly uponNo bleed occurs permanent magnets contacting the print No strikethroughInk heaters medium or a transfer occurs consume power roller. Longwarm-up time Oil Oil based inks are High solubility High viscosity: AllIJ series ink extensively used in medium for some this is a significantjets offset printing. They dyes limitation for use in have advantages inDoes not cockle ink jets, which improved paper usually require acharacteristics on Does not wick low viscosity. Some paper (especiallyno through paper short chain and wicking or cockle). multi-branched oilsOil soluble dies and have a sufficiently pigments are required. lowviscosity. Slow drying Microemulsion A microemulsion is a Stops inkbleed Viscosity higher All IJ series ink stable, self forming High dyethan water jets emulsion of oil, water, solubility Cost is slightly andsurfactant. The Water, oil, and higher than water characteristic dropsize amphiphilic soluble based ink is less than 100 nm, dies can be usedHigh surfactant and is determined by Can stabilize concentration thepreferred curvature pigment required (around of the surfactant.suspensions 5%)

1. An inkjet printhead having a plurality of nozzle arrangements forejecting ink onto a printing medium, each nozzle arrangement comprising:a substrate defining an ink chamber having an ink inlet and a pluralityof ink ejection ports, the chamber being in fluid communication with anink supply channel in the printhead via the ink inlet; a pivot anchorarranged on the substrate; and a moveable actuator fast with the pivotanchor and arranged to cause selective ejection of ink from any one ofthe ejection ports while simultaneously causing an inflow of ink fromthe ink supply channel into the chamber via the ink inlet.
 2. The inkjetprinthead of claim 1, wherein each movable actuator incorporates athermal bend actuator arranged within the associated chamber, thethermal bend actuator being configured to undergo movement due tothermal expansion.
 3. The inkjet printhead of claim 2, wherein eachthermal bend actuator has a beam supporting a paddle, the beam andpaddle being arranged so that movement of the paddle from a quiescentposition towards one of the ejection ports causes the ejection of inkthrough that ejection port.
 4. The inkjet printhead of claim 3, whereinthe beam has a plurality of parallel co-extensive resistor elementsarranged so that differential electrical actuation of the resistorelements creates differential thermal expansion of the beam which causesthe movement of the paddle from the quiescent position.
 5. The inkjetprinthead of claim 4, wherein the beam further has a core extendingcentrally of the resistor elements, the core being formed of materialthat substantially thermally insulates each of the resistor elementsfrom one another.
 6. The inkjet printhead of claim 5, wherein thematerial of the core is glass and a material of each of the resistorelements is a copper nickel based alloy.
 7. The inkjet printhead ofclaim 5, wherein the chamber has two ink ejection ports and the thermalbend actuator has two resistor elements on opposite sides of the coresuch that the paddle can be moved selectively in opposite directionsfrom the quiescent position.